An anchor rod which can be used, for example, to reinforce or anchor concrete elements is, in practice, regularly made of metal. Through a suitable surface structuring, for example in the circumferential direction or a bead-shaped formation and groove-like depressions extending at an angle thereto, a form-fitting adhesion effect can be generated between an anchor rod of that type and a concrete element, in which the anchor rod is embedded. In contrast to anchor rods with a suitable surface profiling, only a significantly lower adhesion effect can be obtained with anchor rods which have a smooth rod surface, which adhesion effect can regularly be insufficient for a use of such rods for the reinforcement and anchoring of concrete elements.
Individual attempts have been undertaken to produce such types of anchor rods out of a suitable fiber composite material. An anchor rod produced out of a suitable fiber composite material can have a low distinct weight, and simultaneously a high mechanical load-bearing capacity. In addition, an anchor rod out of a composite fiber material has a very good resistance to moisture and effects of the weather.
Various methods, with which a surface profiling can be effected by a rod-shaped composite fiber material, are described, for example, in the publication “Verbundverhalten von GFK-Bewehrungsstäben and Rissentwicklung in GFK-stabbewehrten Betonbauteilen” by Mr. Raimo Füllsack-Köditz (Institut für konstruktiven Ingenieurbau Bauhaus-Universität Weimar, November 2004). The rod surface can be roughened, for example, by sand blasting. It is likewise possible to provide the rod surface with a surface profiling via a sand coating. A significantly more strongly varying surface profiling can be effected via a loose or tight banding of the rods with fibers, or via an interweaving of the fibers embedded within an anchor rod. It is also conceivable that an anchor rod with an initially smooth surface subsequently receives a surface profiling via the milling of a groove structure, or via the development of a projecting rib structure with the help of additionally applied synthetic resin.
Subsequently applied rib structures out of synthetic resin, which have no connection to the fibers embedded in the anchor rod, can already be sheared off in a low tensive or compressive stress. Through the milling of a rib or thread structure in an anchor rod initially produced with a smooth rod surface, the fibers extending in this area will be damaged or separated, and the fiber adhesion effect inside of the anchor rod, in particular in the region of the surface profiling, will be significantly weakened. It has been shown that the anchor rods provided with a surface profiling with a method of such type can generate or ensure no sufficient adhesion effect to a surrounding concrete element for many application areas. It is presently technically hardly possible, starting from a smooth anchor rod, to subsequently generate a surface profiling, which can effect or ensure a sufficient adhesion effect for anchor rods in concrete elements.
The amount of time necessary for a curing of the matrix material is significant. The generation of the surface profiling is very burdensome and cost-intensive in the known production methods, and particularly in a loose or tight banding of the anchor rods, or in the interweaving of the fibers embedded in the anchor rod during the production thereof. These types of anchor rods out of a fiber composite material, which have a very high tensile strength and are impervious to effects of the weather, in contrast to anchor rods out of metal, are, in practice, hardly used for construction work or restoration work also for these reasons, despite the advantageous characteristics.
That is why it is considered as one object of the present invention to provide an as simple and cost-effective as possible feasible method for producing anchor rods from a fiber composite material.